Ventricular late potentials and myocardial fibrosis in hypertrophic cardiomyopathy.

AIMS: Ventricular late potentials (VLPs) represent delayed conduction due in part to myocardial fibrosis. We sought to examine the relationship of signal-averaged electrocardiography findings with myocardial fibrosis as assessed by cardiac magnetic resonance (CMR) in patients with hypertrophic cardiomyopathy (HCM). METHODS: This study consisted of 41 HCM patients with sinus rhythm who had undergone risk assessment including CMR and signal-averaged electrocardiography such as VLPs, filtered QRS duration, low amplitude signal duration of the terminal filtered QRS below 40 µV (LAS), and root mean square voltage of the late 40 ms of the filtered QRS (RMS). The concordance rate between VLPs and myocardial fibrosis as assessed by CMR was examined. RESULTS: Late gadolinium enhancement (LGE) on CMR was detected in 13 patients, and VLPs were detected in 14. Filtered QRS duration, LAS, RMS, and VLPs were not associated with LGE. The results of LGE and VLPs were concordant in 26 patients, whereas 15 exhibited discordance. Patients with discordance had a higher maximum wall thickness (24.1 ±â€¯4.0 mm versus 21.0 ±â€¯5.9 mm, p < 0.05), higher LGE volume (2.3 ±â€¯1.2 g/cm versus 0.0 ±â€¯0.8 g/cm, p < 0.01), lower LGE volume/the total number of sites with LGE (1.5 ±â€¯0.7 versus 3.1 ±â€¯2.8, p < 0.01), and predominant LGE location of the interventricular septum and anterior wall (60% versus 8%, p < 0.01) than patients with concordance. CONCLUSION: VLPs were not a reliable marker for the detection of myocardial fibrosis as assessed by LGE on CMR in our cohort of patients with HCM. CONDENSED ABSTRACT: Ventricular late potentials on signal-averaged electrocardiography represent delayed conduction due in part to myocardial fibrosis but were not an alternative to cardiac magnetic resonance for detecting myocardial fibrosis in patients with hypertrophic cardiomyopathy.

The perfusion index is a useful screening tool for peripheral artery disease.

The number of people with peripheral artery disease (PAD) has been increasing globally; therefore, it is important to explore more options to screen patients who are at a risk of developing PAD. The perfusion index (PI) represents the degree of circulation through the peripheral tissues and is measured noninvasively. We investigated the correlation between the PI and ankle-brachial index (ABI) to explore whether the PI could be used a screening tool for PAD. This cross-sectional study included 390 patients. We measured the ABI and PI for all patients. The median ABI value was 1.06 (0.92-1.13); the PI was 1.7% (0.9-3.5). The PI was higher in men than in women (P < 0.0001). The PI was positively correlated with the estimated glomerular filtration rate and ABI in both men and women. The sensitivity and specificity of the PI to predict PAD (ABI ≤0.9) were 90.0% and 80.3%, respectively, and the cutoff PI value was 1.5% in men. The sensitivity and specificity of the PI to predict PAD were 82.1% and 79.2%, respectively, and the cutoff PI value was 1.1% in women. PI could be a reliable screening tool for diagnosing PAD because it does not restrict the patient's mobility, can be completed in a short time period, and is associated with reduced costs.

Third and Fourth Heart Sounds and Myocardial Fibrosis in Hypertrophic Cardiomyopathy.

BACKGROUND: The 4th heart sound (S4) is commonly heard in patients with hypertrophic cardiomyopathy (HCM). The 3rd heart sound (S3) is also audible in HCM patients regardless of the presence or absence of heart failure. These extra heart sounds may be associated with myocardial fibrosis because myocardial fibrosis has been suggested to affect left ventricular compliance.Methods and Results:The present retrospective study evaluated 53 consecutive HCM patients with sinus rhythm who had no symptoms of heart failure and underwent an initial assessment including phonocardiography, echocardiography, and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI). S3 was detected on phonocardiography in 13% of all patients, and S4 was recorded in 75% of patients. Patients with S3 had a higher incidence of LGE and larger LGE volumes (86% and 11.5±2.4 g/cm, respectively) than patients without S3 (33% and 2.5±0.8 g/cm, respectively; P=0.02 and P=0.002). The presence of S4 was not associated with MRI findings, including the incidence of LGE and LGE volume. The diagnostic value of S3 for the detection of LGE was highly specific (97%), with a low sensitivity (29%). CONCLUSIONS: Myocardial fibrosis, as assessed by LGE, was associated with S3 but not with S4 in patients with HCM. These results may contribute to the risk stratification of patients with HCM.

Electrocardiographic changes as a marker of improved subendocardial ischemia in a patient with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) patients sometimes develop subendocardial ischemia without coronary artery stenosis. We report a case of non-obstructive HCM, in which electrocardiographic changes were observed with improvement of subendocardial ischemia. A 76-year-old man presented with chest pain on exertion. The electrocardiogram revealed left ventricular (LV) hypertrophy with repolarization abnormalities. No coronary stenosis was found on computed tomography angiography, but thallium-201 exercise scintigraphy revealed transient LV cavity dilation after exercise, consistent with subendocardial ischemia. His chest symptoms disappeared after starting verapamil. Transient LV cavity dilation improved without a reduction in exercise tolerance, as did electrocardiographic abnormalities without any changes on echocardiography.

Notched QRS for the assessment of myocardial fibrosis in hypertrophic cardiomyopathy.

BACKGROUND: Patients with hypertrophic cardiomyopathy (HCM) sometimes develop myocardial fibrosis in association with adverse cardiovascular events. Electrocardiography (ECG) could provide helpful information on myocardial fibrosis in HCM, as in coronary artery disease. METHODS AND RESULTS: A total of 60 patients with HCM without bundle branch block underwent cardiac magnetic resonance imaging (CMR). The extent or location of late gadolinium enhancement (LGE) was examined in relation to 12-lead ECG. A notch on QRS was defined as at least 2 consecutive spikes in the same polarity with a reversal of direction ≥90° and the initial negative deflection ≥0.05 mV. LGE was associated with notched QRS, leftward QRS axis, and prolonged QRS duration, but not with any other findings such as abnormal Q waves, R-wave amplitude, or ST-T changes. Notched QRS was most useful in determining the presence or absence of myocardial fibrosis, with a sensitivity of 70% and a specificity of 81% using a cut-off of the number of leads with notched QRS ≥2. The number of notched QRS leads was positively correlated with LGE volume (P<0.01) and the lead distribution of notched QRS was informative about the location of LGE. CONCLUSIONS: A notch on QRS was useful in estimating myocardial fibrosis as assessed on CMR LGE in HCM patients without bundle branch block.

Right bundle branch block and ventricular septal fibrosis in patients with hypertrophic cardiomyopathy.

BACKGROUND: Right bundle branch block (RBBB) is associated with ventricular septal fibrosis in patients with hypertrophic cardiomyopathy (HCM) after alcohol septal ablation, but little data are available in HCM patients without a history of septal ablation. METHODS: Magnetic resonance late gadolinium enhancement (LGE) was performed in 59 HCM patients with no history of alcohol septal ablation. The location and extent of LGE were examined in relation to electrocardiographic features including RBBB. RESULTS: LGE volume was higher in 7 HCM patients with RBBB (7.3±7.4g/cm) than in patients without RBBB (2.9±7.4g/cm, p=0.016). LGE volume was positively correlated to QRS duration of RBBB (correlation coefficient=0.93, p=0.023). The diagnostic value of RBBB was highly specific for the detection of LGE in the ventricular septum, with sensitivity 21% and specificity 94%. CONCLUSIONS: The presence of RBBB may be a simple marker for detecting ventricular septal fibrosis in HCM patients who had no history of alcohol septal ablation. Further studies are necessary to confirm our findings.

Holter monitoring and long-term prognosis in hypertrophic cardiomyopathy.

OBJECTIVES: Limited data are available regarding Holter monitoring for cardiovascular events except for ventricular tachycardia as a risk marker for sudden death in hypertrophic cardiomyopathy (HCM). We aimed to examine Holter findings in relation to the long-term prognosis in patients with HCM. METHODS: Ambulatory Holter monitoring was performed in 106 HCM patients with sinus rhythm. All were prospectively followed for the composite endpoint of sudden death, cardiovascular death, and hospitalization for heart failure or stroke associated with atrial fibrillation. RESULTS: Cardiovascular events occurred in 19 patients during a mean follow-up of 10.1 years. Neither arrhythmia information nor autonomic information as assessed by heart rate variability and turbulence significantly differed between HCM patients with and without cardiovascular events. Average heart rates were lower in HCM patients with cardiovascular events (64.7 ± 11.2 beats/min) than in those without (73.7 ± 10.2 beats/min, p = 0.001). Multivariate Cox proportional hazards regression analysis after adjustment for baseline characteristics showed that lower average heart rate remained an independent predictor of cardiovascular events (HR: 0.47 per 10 increase; 95% CI: 0.25-0.87; p = 0.016). CONCLUSION: Average heart rate on Holter monitoring predicted long-term prognosis in our cohort. Further multicenter studies are needed to confirm our results.

Three-layer ultrasonic tissue characterization of the ventricular septum is predictive of prognosis in patients with non-obstructive hypertrophic cardiomyopathy.

AIMS: A necropsy study of patients with hypertrophic cardiomyopathy (HCM) who died at a young age exhibited marked disarray and fibrosis in the mid-wall layer of the left ventricular (LV) myocardium. We assessed ultrasonic tissue characteristics in the three layers of the ventricular septum (VS), and correlated the result with long-term prognosis in HCM. METHODS AND RESULTS: The magnitude of cyclic variation of integrated backscatter (CV-IB) was calculated in the three layers of the VS and the whole aspect of the LV posterior wall in 58 non-obstructive HCM patients and 20 healthy controls. All HCM patients were prospectively followed for an average period of 7.1 years for the occurrence of cardiac death or hospitalization due to heart failure. Each CV-IB of four regions was lower in HCM patients than in controls (all P < 0.01). CV-IB of the VS mid-wall layer was lower in 14 HCM patients with cardiac events than in patients without (5.4 ± 0.6 vs. 7.4 ± 0.5 dB, P = 0.033) although CV-IB of three other regions did not differ between the two groups. The optical cut-off point of %CV-IB <90%, i.e. the ratio of CV-IB in the VS mid-wall layer to the mean value in the layers on both sides, was an independent predictor of cardiac events (hazard ratio, 6.12; 95% confidence interval, 1.62-66.6; P = 0.013), with a positive predictive value of 44% and particularly with a high negative predictive value of 91%. CONCLUSION: Patients with non-obstructive HCM are not likely to undergo cardiac events in the near future, when the CV-IB value is not significantly lower in the VS mid-wall layer than in the layers on both sides.

Kinetics of Thallium-201 in Acute Phase of Myocardial Infarction: A Case Report.

BACKGROUND Thallium-201 has been widely used in clinical practice for the management of coronary heart disease, but little is known regarding its kinetics in the acute phase of myocardial infarction. CASE REPORT We report a 78-year-old man who developed acute inferior myocardial infarction during exercise thallium-201 scintigraphy. The patient underwent exercise testing with thallium-201 myocardial scintigraphy because of a single episode of chest pain. The workload was started with 25 watts and increased by 25 watts every 2 min on a bicycle ergometer with continuous monitoring of 12-lead electrocardiography. Thallium-201 was injected intravenously at 85% of the age-predicted maximal heart rate, and ST-segment elevations refractory to medication subsequently developed in the inferior leads, followed by chest pain. Scintigraphic image acquisition was deferred and he was transferred to the catheter laboratory in this hospital. Emergency coronary angiography showed occlusion in the right coronary artery, and stent implantation was successfully performed. The peak level of creatine kinase in the clinical course was 201 U/l. Scintigraphic images obtained 4 h after the onset of ST-segment elevation showed severely reduced activity in the left ventricular inferior wall, with partial redistribution 24 h later. Follow-up imaging performed 4 months later revealed increased accumulation of thallium-201 in the inferior wall. CONCLUSIONS Our case highlights the kinetics of thallium-201 during acute myocardial infarction.

Chronotropic incompetence and autonomic dysfunction in patients without structural heart disease.

AIMS: An attenuated heart rate response to exercise, termed chronotropic incompetence (CI), has been reported to be an independent predictor of cardiovascular mortality. We examined the change in autonomic function during exercise testing and correlated the results with CI. METHODS AND RESULTS: Exercise testing using a bicycle ergometer was performed in 172 patients who had no evidence of cardiac disease. Chronotropic incompetence was defined as the failure to achieve 85% of the age-predicted maximum heart rate, heart rate reserve <80%, or chronotropic response index <0.80. We analysed the relationship between CI and the change in two components of heart rate variability during exercise testing: high-frequency (HF) component (0.15-0.40 Hz) as an index of vagal modulation and the ratio of low-frequency (LF) component (0.04-0.15 Hz) to HF component as an index of sympathovagal balance. Heart rate variability indexes before exercise were similar in patients with and without CI. Percentage changes after exercise in the ratio of LF to HF component were higher in patients with CI than in those without CI (84 +/- 15 vs. 41 +/- 16%, P < 0.05), whereas percentage changes in an HF component were similar in the two groups. CONCLUSION: Our data suggested that CI in patients without structural heart disease was mainly caused by a pathophysiological condition in which sympathetic activation was not well translated into heart rate increase. Further study is needed to determine the post-synaptic sensitivity of the beta-adrenergic receptor pathway in relation to CI.

Vagal enhancement as evidence of residual ischemia after inferior myocardial infarction.

BACKGROUND: Acute inferior myocardial infarction (MI) often induces transient sinus bradycardia through vagal enhancement, known as Bezold-Jarisch reflex, which is explained by preferential distribution of vagal nerve in the inferior wall. We examined vagal activity in relation to the occurrence of residual ischemia in patients with old inferior MI and assessed its diagnostic usefulness. METHODS: Exercise myocardial scintigraphy was performed in 15 patients with old inferior MI, 19 angina pectoris (AP) patients with inferior ischemia but no MI, and 32 control subjects who had no evidence of cardiac disease. We analyzed the connection of residual ischemia in old MI with ST-segment response to exercise and with vagal activity as determined by coefficient of component variance of high frequency (CCV(HF)). RESULTS: Exercise-induced percentage change in CCV(HF) was higher in patients with old MI and residual ischemia (18.8 +/- 13.5%) and AP (5.5 +/- 9.7%) than old MI but no residual ischemia (-24.1 +/- 4.9%) or control (-22.8 +/- 4.5%, P = 0.006). Percentage change in CCV(HF) > -5% had a good diagnostic value for the detection of residual ischemia in patients with old inferior MI with sensitivity of 83%, specificity of 89%, accuracy of 87%, and positive likelihood ratio of 7.50, which was higher than that of ST-segment depression (67%, 50%, 56%, and 1.33). CONCLUSIONS: Vagal enhancement was associated with residual ischemia in old inferior MI as well as inferior AP. Measurement of CCV(HF) is useful in improving the diagnostic reliability of exercise electrocardiography in patients with old inferior MI.

Onset of new diastolic murmur as a sign of bioprosthetic valve dysfunction: A case report.

The diagnosis of prosthetic valve dysfunction remains challenging because visualization is limited due to artifacts on echocardiography. We herein report a case of bioprosthetic valve dysfunction, in which cardiac auscultation was useful as an initial clue to the diagnosis. An 81-year-old man, who had undergone bioprosthetic aortic valve replacement due to aortic stenosis 10 years earlier, presented to the emergency department with chest discomfort. Cardiac auscultation revealed a newly developed diastolic murmur, although no diastolic murmurs were previously detected on auscultation or phonocardiography. There were no notable changes in electrocardiography, chest radiograph, laboratory tests, or echocardiography except for trivial aortic regurgitation. His hemodynamic status progressively deteriorated due to prosthetic valve dysfunction, which was later confirmed on echocardiography, and aortic valve re-replacement was semi-urgently performed with success. The diastolic murmurs disappeared after surgery. .

A Case of Isolated Septal Myocardial Infarction: Myocardial Perfusion-metabolism Mismatch as a Tool for Diagnosis.

Isolated septal myocardial infarction is an uncommon condition with diagnostic difficulty due to small infarction size and anatomical variations. We report a case of isolated septal myocardial infarction, in which the diagnosis was confirmed not by electrocardiographic, echocardiographic, or angiographic findings, but by nuclear imaging. A 46-year-old man with chest discomfort exhibited ST-segment elevations in leads V1 and V2, and borderline abnormalities of the septal wall motion on echocardiography. Emergency coronary angiography demonstrated delayed flow in the second septal branch of the left anterior descending coronary artery. Intravascular ultrasound showed plaque in the proximal portion of the septal branch without evidence of plaque rupture. No balloon angioplasty or stent implantation was required because the flow delay in the septal branch disappeared after the intravascular ultrasound procedure. Myocardial perfusion-metabolism mismatch, as assessed by resting thallium-201 and iodine-123-beta-methyl-p-iodophenyl-pentadecanoic acid, was seen in the mid-septal region.

R-wave amplitude response to myocardial ischemia in hypertrophic cardiomyopathy.

BACKGROUND AND PURPOSE: R-wave amplitude change during exercise has been reported to enhance diagnostic value for myocardial ischemia in coronary heart disease. METHODS: We summed up R-wave amplitude in all the 12 leads during exercise testing and correlated the results with regional myocardial ischemia or diffuse subendocardial ischemia as detected by scintigraphy in 49 patients with hypertrophic cardiomyopathy (HCM) and 16 controls. RESULTS: The sum of R-wave amplitude decreased during exercise in patients with HCM (mean, 12.4 mV to 11.7 mV, P < .01) as well as in controls (8.0 mV to 7.7 mV, P < .05). Percent changes in the sum of R-wave amplitude did not differ between 4 subgroups of patients with HCM: one having both regional and subendocardial ischemia, one only the former, one only the latter, and one neither of them (mean, 6.5%, 7.7%, 4.6%, and 5.1%; P = .79). CONCLUSIONS: R-wave amplitude response to exercise failed to demonstrate myocardial ischemia in our patients with HCM.